title: Volume independence in the large N limit and an emergent fermionic symmetry.
abstract: Large-N volume independence in circle-compactified QCD with adjoint Weyl fermions implies the absence of any phase transitions as the radius is dialed to arbitrarily small values. This class of theories is believed to possess a Hagedorn density of hadronic states. It turns out that these properties are in apparent tension with each other, because a Hagedorn density of states typically implies a phase transition at some finite radius. This tension is resolved if there are degeneracies between the spectra of bosonic and fermionic states, as happens in the N(f) = 1 supersymmetric case. Resolution of the tension for N(f) >1 then suggests the emergence of a fermionic symmetry at large N, where there is no supersymmetry. We can escape the Coleman-Mandula theorem since the N = ∞ theory is free, with a trivial S matrix. We show an example of such a spectral degeneracy in a nonsupersymmetric toy example which has a Hagedorn spectrum.
authors.affiliation: Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA.
authors.forename: Gökçe
authors.initials: G
authors.lastname: Başar
authors.forename: Aleksey
authors.initials: A
authors.lastname: Cherman
authors.forename: Daniele
authors.initials: D
authors.lastname: Dorigoni
authors.forename: Mithat
authors.initials: M
authors.lastname: Ünsal